The present invention relates to display devices, and in particular, to reconfiguration of display devices according to their current environment.
Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
A color appearance model (CAM, which may also be referred to as a “color model”) is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components. When this model is associated with a precise description of how the components are to be interpreted (viewing conditions, etc.), the resulting set of colors is called color space. Examples of color spaces include the tristimulus color space, the XYZ color space (developed by the International Commission on Illumination [CIE], and which may also be referred to as the “CIE 1931 color space”), the red-green-blue (RGB) color space, the hue-saturation-value (HSV) color space, the hue-saturation-lightness (HSL) color space, the long-medium-short (LMS) color space, and the cyan-magenta-yellow (CMY) color space.
CAMs are useful to match colors under different environment conditions that otherwise might be perceived to be different, according to the human visual system (HVS). In particular, a color captured (e.g., in an image) under one set of conditions may be perceived as a different color by an observer viewing that color in another set of conditions. The following are examples of factors that can contribute to perceptible color mismatches: the different chromacities and/or luminance levels of different illuminants, different types of devices used to display the color, the relative luminance of the background, different conditions of the surrounding environment, as well as other factors. Conventional CAMs aim to compensate for these factors by adjusting an image viewed with a destination set of conditions so that it appears to be the same color at which it was captured with a source set of conditions. Thus, CAMs can be used to convert a patch of color seen in one environment (e.g., the source environment) to an equivalent patch of color as it would be observed in a different environment (e.g., the target environment).
As an example, consider the most recent CAM ratified by CIE, which is referred to as CIECAM02. CIECAM02 provides a limited ability to modify a color appearance model based on the environment of the display device. Three surround conditions (namely Average, Dim and Dark) provide the parameters given in TABLE 1:
TABLE 1SurroundSurroundconditionratioFcNcApplicationAverageSR > 0.21.00.691.0Viewing surface colorsDim0 < SR < 0.20.90.590.95Viewing televisionDarkSR = 00.80.5250.8Using a projector in a darkroom
In TABLE 1, the surround ratio SR tests whether the surround luminance is darker or brighter than medium gray (0.2). The parameter F is a factor that determines a degree of adaptation. The parameter c is a factor that determines the impact of the surroundings. The parameter Nc is a chromatic induction factor. The color appearance model may be modified according to the parameters corresponding to the appropriate surround conditions.